Prediction Of Difficult Laryngoscopy Research Articles

Prediction of difficult laryngoscopy and/or intubation among morbidly obese patients: Upper lip bite test versus modified Mallampati classification.

We aim to compare the upper lip bite test with the modified Mallampati test as predictors of difficult laryngoscopy and/or difficult intubation among morbidly obese patients. A total of 500 morbidly obese patients (body mass index > 40 kg/m2) undergoing general anaesthesia with tracheal intubation are included in this prospective single-blinded observational clinical study. The preoperative airway assessment is obtained by the modified Mallampati test and upper lip bite test. The difficulty of laryngoscopy is assessed by an experienced anaesthetist in patients adequately anaesthetised and fully relaxed. The view is classified according to Cormack and Lehane's classification. Modified Mallampati test III or IV and upper lip bite test III are considered positive tests. Difficult laryngoscopy is defined as Cormack and Lehane's classification III and IV, whereas difficult endotracheal intubation is defined as an intubation difficulty scale ⩾ 5. The incidences of Cormack and Lehane's classification III and IV and intubation difficulty scale ⩾ 5 are 9.4% and 11.8% respectively. The specificity, positive predictive value and accuracy are higher with the upper lip bite test. The combination of the upper lip bite test and the modified Mallampati test improved these measures. The likelihood ratio + was significantly higher for the upper lip bite test (6.35 and 9.47) than for the modified Mallampati test (3.21 and 3.16). The upper lip bite test is a test with high sensitivity, specificity, negative predictive value and accuracy making it a favourable test for identifying easy and difficult intubations and laryngoscopies in morbidly obese patients.

Distance from skin to epiglottis measurement with ultrasonography as a predictor of difficult laryngoscopy: A diagnostic test accuracy meta-analysis

BackgroundThe studies investigating distance from the skin to epiglottis measurements by ultrasonography (US-DSEM) for prediction of difficult laryngoscopy are inconclusive and non-standardised. AimWe aimed to assess the diagnostic test accuracy (DTA) of US-DSEM relative to Cormack Lehane 3–4 for diagnosing difficult laryngoscopy using a meta-analysis method. MethodStrict inclusion criteria were used to provide clear definition of how to measure US-DSEM. PubMed, Cochrane Library, Embase and Google Scholar were searched for papers published between January 2005 and March 2021 to perform a systematic review and DTA meta-analysis. Publications reporting data on US-DSEM in difficult laryngoscopy prediction in adults with normal airway were included. Exclusions were obese or pregnant patients and patients with difficult airway predictors and those in which the measurements were made in a position other than supine and neutral positions. The pooled sensitivity, specificity, positive/negative likelihood ratios (PLR/NLR), diagnostic odds ratio (DOR), and area under the hierarchic summary receiver operating characteristics curve (AU-HSROC) were determined. Results1244 patients from nine studies were included. Pooled sensitivity: 0.68 (95%CI 0.39–0.87), specificity: 0.76 (95%CI 0.68–0.83), PLR: 2.87 (95%CI 2.20–3.73), NLR: 0.42 (%95CI 0.20–0.87), DOR: 6.80 (95%CI 2.72–17.3), and AU-HSROC: 0.79 (0.75–0.82) were the results. No threshold effect (r = 0.53, p = 0.137) and publication bias (p = 0.540) existed. ConclusionThis meta-analysis showed that US-DSEM measured with linear probe placed transversely at the thyrohyoid membrane level with midline approach and neutral head position is accurate and has diagnostic value in predicting difficult laryngoscopy. However, its sensitivity and specificity are not sufficient to replace clinical tests.

Prediction of difficult laryngoscopy / difficult intubation cases using upper airway ultrasound measurements in emergency department: a prospective observational study

IntroductionDifficult laryngoscopy and intubation are serious problems among critically ill patients in emergency department (ED) so utility of a rapid, accurate and noninvasive method for predicting of these patients are necessary. Ultrasonography has been recently used in this regard and this study was conducted to investigate the correlation of some introduced upper airway ultrasound parameters with difficult laryngoscopy / difficult intubation in patients referred to the ED.MethodIn this prospective observational study all patients ≥ 18-year-old who had an indication for rapid sequence intubation (RSI) were included. Ultrasound parameters including Hyoid Bone Visibility (HBV), Distance from Skin to Hyoid Bone (DSHB), Distance from Skin to Vocal Cords (DSVC), Distance from Skin to Thyroid Isthmus (DSTI), and Distance between Arytenoids Cartilages (DBAC) were measured in all cases. The patients underwent RSI and thereafter the patients’ baseline characteristics, Cormack-Lehane grade, number of attempted laryngoscopy were recorded in a pre-prepared check list and compared with measured ultrasound parameters. The “difficult laryngoscopy” was defined as Cormack-Lehane classification grades III/IV; and need for more than 3 intubation attempts was considered as “difficult intubation”.ResultsOne hundred and twenty-three patients (52% male) were included of whom 10 patients (8.1%) were categorized as difficult laryngoscopy cases; and just 4 (3.3%) cases underwent more than 3 laryngoscopy attempts who considered as difficult intubation cases. The mean age of the patients in non-difficult and difficult intubation groups were 69.2 ± 15.16 and 68.77 ± 17.37 years, respectively (p > 0.05). There was no significant relationship between difficult laryngoscopy and HBV (p = 0.381) but has significant correlation with difficult intubation (p = 0.004). The DSHB had a significant correlation with difficult laryngoscopy (p = 0.002) but its correlation with difficult intubation was not significant (p = 0.629). The DSVC and DSTI had a significant relationship with both difficult laryngoscopy (p = 0.003 and p = 0.001), and difficult intubation (p = 0.025 and p = 0.001). The DBAC had not significant correlation neither with the difficult laryngoscopy (p = 0.142), nor with difficult intubation (p = 0.526).ConclusionThe findings showed that ultrasound parameters including soft tissue DSHB, DSVC and DSTI could be proper predictors of difficult laryngoscopy. Also, HBV, DSVC and DSTI may be proper predictors for difficult intubation. But DBAC was not useful in this regard.

Evaluation of ratio of height to thyromental distance as a predictor of difficult visualization of larynx: A prospective observational single center study

BackgroundRatio of height to thyromental distance (RHTMD) is a relatively new predictor of difficult visualization of larynx (DVL). Studies on Indian population are limited and none is carried out in the northeastern part of India. AimsThe primary aim was to assess the performance of RHTMD as a predictor of DVL and compare its predictive performance with modified Mallampati test. The secondary aim was to compare the performance of RHTMD with sterno-mental distance, inter-incisor distance and upper-lip bite test, as a predictor of DVL. We also aimed to evaluate the performance of RHTMD as a predictor of Intubation difficulty scale (IDS) > 5. MethodsIn this prospective, observer blinded, single center study, adult patients of either sex scheduled to receive general anaesthesia with tracheal intubation were enrolled after permission from institutional committee. RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test wereassessed pre-operatively by a single examiner trained in the airway indices but not involved in laryngoscopy. On the day of surgery, laryngoscopy was performed by a trainee anaesthesiologist with minimum two years of experience who was blinded to the airway indices noted by the examiner preoperatively. The Cormack-Lehane grading and subsequent difficulty in intubation as per Intubation difficult scale was noted. RHTMD≥23.5, inter-incisor distance ≤ 4 cm, sterno-mental distance ≤12.5 cmand upper lip bite test class 3 were considered as predictor of difficult laryngoscopy. ResultsThe incidence of DVL and difficult intubation in our study was 6.57% (4.85 %-8.82%, 95% CI) and 1.37% (0.68%–2.7%, 95% CI) respectively. The sensitivity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test were 65.12%, 53.49%, 18.6%, 30.23% and 72.09% respectively. Specificity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 90.51%, 90.34%, 97.22%, 98.20%, and 89.69% respectively. Area under the ROC curve was highest for RHTMD (0.881). Area under the ROC curve for modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 0.742, 0.621, 0.757 and 0.815 respectively. RHTMD had a sensitivity, specificity, and AUC for predicting difficult intubation of 66.67%, 87.60%, and 0.908 respectively. ConclusionWe primarily conclude that RHTMD has a good predictive performance and is similar to modified Mallampati test as a predictor of difficult visualization of larynx. We secondarily conclude that RHTMD is a better predictor of difficult visualization of larynx compared to sterno-mental distance, inter-incisor distance and upper-lip bite test. It is also an excellent predictor of IDS> 5.

Evaluation of Palm Print Sign and Prayer Sign in Prediction of Difficult Laryngoscopy in Diabetic Patients.

Laryngoscopy or endotracheal intubation in diabetic patients due to impaired mobility of the Atlanto-occipital joint owing to non-enzymatic glycosylation in connective tissue has always been a problem. A difficult laryngoscopy can disrupt the intubation process; therefore, it is valuable to predict difficult laryngoscopy using some anatomical criteria before general anesthesia. The present study discussed the diagnostic value of two tests, palm print sign and prayer sign, in the prediction of laryngoscopy difficulty. Design: A diagnostic test and cross-sectional analytical design were used in this study. Setting: The study population included 200 patients with type 2 diabetes who were candidates for surgery under general anesthesia. Before surgery, the patients were examined regarding the airway status, Mallampati classification, head extension rate, thyromental distance, body mass index, upper lip biting test, and two palm print sign and prayer sign tests. All the diagnostic tests were compared to the Cormack test result for difficult airways regarding their sensitivity and specificity in difficult laryngoscopy. The highest sensitivity was related to the Mallampati test, prayer sign test, and palm print sign test (100%). Furthermore, the mouth-opening test had the highest specificity (100%). The highest accuracy was reported for Mallampati, palm print sign, and prayer sign tests (> 86%). Among the tests studied to predict difficulty in laryngoscopy in diabetic patients, Mallampati and palm print sign tests have good sensitivity, specificity, and accuracy. Studies with a larger sample size are suggested to obtain more accurate results.

Evaluation of neck measurements and their correlation with prediction of difficult laryngoscopic view

INTRODUCTION: Preoperative assessment of various anatomic and clinical features helps in identifying potentially difficult laryngoscopy and intubation in advance allowing the anesthetist to be prepared for such a scenario. Though “ Short Neck” is a commonly used term in airway assessment indicating the possibility of a difficult airway. there is a lack of clarity regrading the cut off value and the association of different neck lengths (Anterior, Posterior and Lateral) to the laryngoscopic view. AIM : Evaluation of anterior, posterior and lateral neck length in neutral and extended positions and correlate each measurement with prediction of difficult laryngoscopic view. MATERIALS AND METHODS : This prospective observational study was conducted on 150 patients belonging to American Society of Anesthesiologists (ASA) grade 1/11 , aged 18-65 years with body mass index (BMI) 18 to 35 kg/m2,scheduled to undergo elective surgeries under general anaesthesia with endotracheal intubation. Each subject’s anterior,lateral and posterior neck lengths (ANL,LNL,PNL) were measured pre operatively. Direct laryngoscopy was done to achieve the best Cormack Lehane(CL) grade using manoeuvres (Backward upward rightward manoeuvre(BURP)/OELM/Change of Blade/Change of pillow height/RAMP positioning) when indicated and the same compared to the measured neck lengths. RESULT : The incidence of difficult laryngoscopy was found to be 18 per cent in our study population. Anterior neck length in neutral position was found to be the best predictor of difficult laryngoscopy, with a threshold of less than or equal to 9 cms. No particular neck length correlated with BMI and age. All the neck lengths showed positive correlation with the height of the subject CONCLUSION : ANL with a cut off criterion of less than or equal to 9 cm in neutral position can used objectively when measuring neck length. All neck lengths showed significant change with neck mobility. Rate of change of both PNL and LNL with head extension position showed significant change in difficult laryngoscopy subjects.

Accuracy of sternomental displacement test and thyromental height test as a predictive measure for difficult airway in elderly surgical patients: a prospective cohort study

ABSTRACT Background Airway assessment before anaesthesia in the elderly is crucial. The delay in endotracheal intubation in this age group can lead to fatal consequences. This study aimed to evaluate the validity of sternomental displacement (SMDD) as a predictor of difficult airway in the elderly and to compare it with the thyromental height test (TMHT). Methods This study included 150 patients aged > 65 years old, ASA i–iii, who were scheduled for elective surgeries under general anaesthesia with endotracheal intubation using conventional laryngoscopy. Cormack–lehane grades iii and iv were assigned as difficult laryngoscopy (DL). Difficult intubation (DI) was defined as insertion of endotracheal tube required more than two attempts or 10 minutes. The primary outcome was the AUROC curve for the SMDD as a predictor of difficult laryngoscopy. Results 14% of our patients showed DL, while 4.7% had DI. SMDD was a good predictor for DL with 0.692 AUC (95% ci: 0.611 − 0.765) at a cut-off value of ≤35 mm, with 71.43% sensitivity, 59.69% specificity, 22.4% PPV and 92.8% NPV. TMHT showed good prediction for DL with 0.794 AUC (95% ci: 0.721–0.856) at a cut-off value of ≤ 49.5 mm. For predicting DI, SMDD showed AUROC (95% ci): 0.814 (0.743–0.873) at a cut-off value ≤35 mm and TMHT had AUROC (95% ci): 0.719 (0.640–0.790) at a cut-off value ≤ 49.5 mm. Conclusion SMDD and TMHT are good objective predictors for DL and di in elderly surgical patients.

Anatomical location of the vocal cords in relation to cervical vertebrae, a new predictor of difficult laryngoscopy: A descriptive cross sectional study

Airway management is among the challenges faced by the anaesthesiologists. There are anatomical and clinical factors, which can predict the difficult laryngoscopy. In this study, the aim was to predict the easy and difficult laryngoscopy preoperatively by assessing the anatomy of patient’s head and neck. The objective was to assess the same by using the magnetic resonance imaging films of the neck. The study included 110 adult patients with existing preoperative magnetic resonance imaging scans of neck. Preoperative anaesthetic assessment was done by using the thyromental distance, sternomental distance, body weight, mouth opening, Mallampati classification and head neck movement. The magnetic resonance imaging scans were screened for slices to visualise the vocal cords. A projection line was drawn to determinethe topography of vocal cords in relation to the cervical vertebrae. The ease of laryngoscopy by Cormack-Lehane grade was then correlated with the vertebral level of the vocal cords.The laryngoscopy was difficult in over weight patients (p<0.001) and with smaller thyromental distance. It was also observed that the laryngoscopy was easy (p<0.001), when the topographical location of vocal cords were related to C5 and hard, when they are at the level of C4 and C6 (p<0.001). Magnetic resonance imaging films of neck could be used to evaluate the potential difficult laryngoscopy, preoperatively. It can be used along with the existing bedside tests like determination of thyromental distance, sternomental distance and modified Mallampati classification.

Acoustic features as novel predictors of difficult laryngoscopy in orthognathic surgery: an observational study.

BackgroundThe evaluation of the difficult intubation is an important process before anaesthesia. The unanticipated difficult intubation is associated with morbidity and mortality. This study aimed to determine whether acoustic features are valuable as an alternative method to predict difficult laryngoscopy (DL) in patients scheduled to undergo orthognathic surgery.MethodsThis study included 225 adult patients who were undergoing elective orthognathic surgery under general anaesthesia with tracheal intubation. Preoperatively, clinical airway evaluation was performed, and the acoustic data were collected. Twelve phonemes {[a], [o], [e], [i], [u], [ü], [ci], [qi], [chi], [le], [ke], and [en]} were recorded, and their formants (f1-f4) and bandwidths (bw1-bw4) were extracted. Difficult laryngoscopy was defined as direct laryngoscopy with a Cormack-Lehane grade of 3 or 4. Univariate and multivariate logistic regression analyses were used to examine the associations between acoustic features and DL.ResultsDifficult laryngoscopy was reported in 59/225 (26.2%) patients. The area under the curve (AUC) of the backward stepwise model including en_f2 [odds ratio (OR), 0.996; 95% confidence interval (CI), 0.994–0.999; P=0.006], ci_bw4 (OR, 0.997; 95% CI, 0.993–1.000; P=0.057), qi_bw4 (OR, 0.996; 95% CI, 0.993–0.999; P=0.017), le_f3 (OR, 0.998; 95% CI, 0.996–1.000; P=0.079), o_bw4 (OR, 1.001; 95% CI, 1.000–1.003; P=0.014), chi_f4 (OR, 1.003; 95% CI, 1.000–1.005; P=0.041), a_bw4 (OR, 0.999; 95% CI, 0.998–1.000; P=0.078) attained a value of 0.761 in the training set, but a value of 0.709 in the testing set. The sensitivity and specificity of the model in the testing set are 86.7% and 63.0%, respectively.ConclusionsAcoustic features may be considered as useful predictors of DL during orthognathic surgery.

Evaluation of thyromental height as a predictor of difficult laryngoscopy and difficult intubation: a cross-sectional observational study

Background and objectivesSeveral anthropometric measurements have been suggested to identify a potentially difficult airway. We studied thyromental height (TMH) as a predictor of difficult laryngoscopy and difficult intubation. We also compared TMH, ratio of height to thyromental distance (RHTMD), and thyromental distance (TMD) as predictors of difficult airway. MethodsThis cross-sectional observational study was conducted in 300 adult surgical patients requiring tracheal intubation. Preoperatively airway characteristics were assessed. Standard anesthesia was administered. Degree of difficulty with mask ventilation, laryngoscopic view, duration of laryngoscopy, and difficulty in tracheal intubation (intubation difficulty scale score) were noted. Multivariate logistics regression analysis was performed to identify independent predictors for difficult laryngoscopy. ResultsLaryngoscopy was difficult in 46 of 300 (15.3%) patients; all 46 patients had Cormack-Lehane grade 3 view. Duration of laryngoscopy was 27........11...s in patients with difficult laryngoscopy and 12.7........3.9...s in easy laryngoscopy; p...=...0.001. Multivariate analysis identified that TMH, presence of short neck, and history of snoring were independently associated with difficult laryngoscopy. Incidence of difficult intubation was 17.0%. A shorter TMH was associated with higher IDS scores; r...=...-0.16, p...=...0.001. TMH and duration of laryngoscopy were found to be negatively correlated; a shorter TMH was associated with a longer duration of laryngoscopy; r...=...-0.13, p...=...0.03. The cut-off threshold value for TMH in our study is 4.4 cm with a sensitivity of 66% and a specificity of 54%. ConclusionThyromental height predicts difficult laryngoscopy and difficult intubation.TMD and RHTMD did not prove to be useful as predictors of difficult airway.

Limited condylar mobility by ultrasonography predicts difficult direct laryngoscopy in morbidly obese patients: An observational study.

Background and Aims:Unpredictable difficult laryngoscopy remains a challenge for anaesthesiologists, especially in morbidly obese patients. The present study aimed to determine the efficacy of different sonographic measures as predictors of difficult laryngoscopy in morbidly obese patients undergoing elective surgery.Methods:This observational study evaluated 70 morbidly obese adult patients (body mass index >35 kg/m2) undergoing elective surgery under general anaesthesia with tracheal intubation. Pre-operative clinical and ultrasonographic variables (anterior condylar translation, tongue thickness, hyomental distance and oral cavity height) associated with difficult direct laryngoscopy ([Cormack Lehane (CL) grade>2]) were analysed. The primary outcome was to determine the efficacy of the above-mentioned sonographic measures as predictors of difficult laryngoscopy (CL grade >2). The secondary outcome compared ultrasonographic predictors with clinical predictors in morbidly obese patients for determining difficult direct laryngoscopy.Results:Amongst the primary outcome measures, limited condylar mobility (anterior condylar translation <9.25 mm) [odds ratio (OR) 0.3, confidence interval (CI):1.04-1.22;P<0.001;area under curve (AUC):0.8] and increased tongue thickness >5.85 cm [OR: 3.2, CI: 1.05–10; P < 0.04; AUC: 0.73] were two independent sonographic predictors for difficult direct laryngoscopy by multivariate logistic regression and receiver operating characteristic curve analyses in morbidly obese patients. The secondary outcome suggested that as compared to clinical predictors such as Mallampati grade and thyromental distance, ultrasonographic variables such as tongue thickness and limited condylar mobility (sensitivity: 56.4%, 70.9%, 66.7% and 93.3%, respectively) better predicted difficult direct laryngoscopy in morbidly obese patients.Conclusion:Limited condylar mobility and increased tongue thickness are independent sonographic predictors of difficult direct laryngoscopy in morbidly obese patients.

Predictive model for difficult laryngoscopy using machine learning: retrospective cohort study

BackgroundBoth predictions and predictors of difficult laryngoscopy are controversial. Machine learning is an excellent alternative method for predicting difficult laryngoscopy. This study aimed to develop and validate practical predictive models for difficult laryngoscopy through machine learning. MethodsVariables for the prediction of difficult laryngoscopy included age, Mallampati grade, body mass index, sternomental distance, and neck circumference. Difficult laryngoscopy was defined as grade 3 and 4 by the Cormack-Lehane classification. Pre-anesthesia and anesthesia data of 616 patients who had undergone anesthesia at a single center were included. The dataset was divided into a base training set (n = 492) and a base test set (n = 124), with equal distribution of difficult laryngoscopy. Training data sets were trained with six algorithms (multilayer perceptron, logistic regression, supportive vector machine, random forest, extreme gradient boosting, and light gradient boosting machine), and cross-validated. The model with the highest area under the receiver operating characteristic curve (AUROC) was chosen as the final model, which was validated with the test set. ResultsThe results of cross-validation were best using the light gradient boosting machine algorithm with Mallampati score x age and sternomental distance as predictive model parameters. The predicted AUROC for the difficult laryngoscopy class was 0.71 (95% confidence interval, 0.59–0.83; p = 0.014), and the recall (sensitivity) was 0.85. ConclusionPredicting difficult laryngoscopy is possible with three parameters. Severe damage resulting from failure to predict difficult laryngoscopy with high recall is small with the reported model. The model’s performance can be further enhanced by additional data training.

Role of Acromioaxillosuprasternal Notch Index (AASI) as a New Predictor of Difficult Visualization of Larynx in Comparison with Modified Mallampati Test

Background: Pre-operative airway assessment should be able to predict potential difficult airway, allowing management plan to be developed ahead of time. Hence this study was aimed to compare Acromio-AxilloSuprasternal Notch Index (AASI), a new simple bedside test with Modified Mallampati Test (MMP) in predicting difficult visualization of larynx. Materials and Methods: After ethical committee clearance and informed written consent, 320 patients of ASA I and II posted for elective surgery under general anaesthesia were included in this study. AASI and MMP were noted during preanaesthetic airway assessment. After induction of anaesthesia, a blinded and experienced anaesthetist did laryngoscopy, intubated the patient and noted Cormack-Lehane(CL) grading of laryngeal view. The data observed was analysed using Receiver operating characteristic curve(ROC) analysis to compare AASI and MMP. A P value less than 0.05 was considered statistically significant. Results: Incidence of Difficult Visualization of Larynx(DVL) in our study was 8.4%. AASI had better Sensitivity(88.89% v/s 22.22%), Specificity(98.63% v/s 95.22%),Positive predictive value (85.71% v/s 26.32%), Negative predictive value (98.97% v/s 93%) and Diagnostic accuracy(97.81% v/s 89.03%) in comparison with MMP respectively (P &lt;0.001) when cut off reference value of 0.56 AASI was taken. Conclusion: AASI is a better predictor of difficult laryngoscopy with a higher sensitivity and positive predictive value in comparison with MMP. Hence AASI can be used as a simple bedside test to predict difficult airway during pre-anaesthetic airway assessment. Keywords: Acromioaxillosuprasternal notch index (AASI); Modified Mallampati test (MMP); Cormack-Lehane (CL) grade; Difficult visualization of larynx (DVL); Airway assessment.

A Novel Test, the Sternomental Distance Ratio, Used as a Predictor of Difficult Laryngoscopy in a Normal Population and in Thyroid Tumor Surgery Patients: A Preliminary Study.

The aim of the present preliminary study was to assess whether the sternomental distance ratio (SMDR) could be suitable as a predictor of difficult laryngoscopy, in both normal surgical patients and patients scheduled to undergo thyroid tumor surgery. Two hundred and twenty-one consecutive adult patients (among them 122 patients with presumed normal airways and 33 patients with thyroid tumors), scheduled to undergo elective surgery under general anesthesia, were included in this study. Physical and airway characteristics, SMDR, difficult laryngoscopy (using Cormack-Lehane scale) and any kind of assisted intubation were assessed. Decreased SMDR demonstrated a strong correlation with difficult laryngoscopy in both thyroid tumor (Kendall's tau-b -0.578 (P=0.004) and normal patients -0.362 (P<0.001). Difficult laryngoscopy was 0 at SMDR>1.9 and 33% at SMDR <1.55 (P<0.001). The higher the SMDR was, the better the glottic view obtained. ? SMDR>1.9 indicates an easy laryngoscopy, whereas SMDR <1.55 indicates a difficult one in both thyroid tumor and normal patients. SMDR is an objective test to assess difficult airway in thyroid surgery.

Ratio of height to thyromental distance: a comparison with mallampati and upper lip bite test for predicting difficult intubation in Pakistani population.

To compare the accuracy of three diagnostic tests in predicting difficult laryngoscopy using Cormack and Lehane grade as the gold standard. The cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from August 2014 to August 2015, and comprised patients who required endotracheal intubation for elective surgical procedures. The primary investigator used ratio of height to thyromental distance, upper lip bite test and the modified Mallampati test for assessing the airway correlated with laryngoscopic view based on Cormack and Lehane grading. Data was analysed using SPSS 19. Of the 383 patients, 59(15.4%) were classified as difficult cases of laryngoscopy. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ratio of height to thyromental distance were 84.7%, 90.1%, 60.9%, 97%, 89.3%; and those the corresponding values for the upper lip bite test were 83.1%, 89.2%, 58.3%, 96.7% and 88.3%. The values for the modified Mallampati test were 30.5%, 84.3%, 26.1%, 86.9% and 79.9% respectively. The area under receiver-operating characteristic curve for the first two tests was significantly more than for the modified Mallampati test (p<0.01). RHTMD and ULBT both are acceptable alternatives for prediction of difficult laryngoscopy as a simple, single bed-side test.

Alveolar cleft and maximum cleft width as predictors for difficult laryngoscopy and intubation in patients with unilateral complete cleft lip and palate

BackgroundCleft lip and palate is one of the commonest congenital anomalies, which have an impact on feeding, speech, and dental development away from the significant psychosocial sequel. Early surgical repair aims to restore appearance and function, and the modern techniques can leave many defects undetectable. Therefore, the anesthetic challenge facing the pediatric airway with such abnormalities is still of a great impact. The aim of our study among 189 patients enrolled is to correlate alveolar gap and maximum cleft width measurements as predictors of difficult laryngoscopy and intubation in infants with unilateral complete cleft lip/palate aging from 1 to 6 months. As a secondary outcome, their weight is to be correlated too as another parameter.ResultsThe alveolar gap and maximum cleft width are both of equal high predictive power (p value ≤ 0.001) with 100% sensitivity for both and specificity of 76.10% and 82.39% respectively, with a cut off value of ≤ 10 mm and 11 mm for these dimensions respectively, and odds ratio of incidence of difficult intubation is 4.18 and 5.68 respectively, while body weight ≤ 5.75 kg has an odds ratio of 2.32.ConclusionAlveolar cleft and maximum cleft width can be used as predictors for anticipation of difficult laryngoscopy and intubation infant patients with unilateral complete cleft lip and palate, while body weight ≤ 5.75 kg increases the risk more than twice.

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English

BACKGROUND A few patients of apparently normal appearance unexpectedly present with great difficulties during intubation which may lead to potentially serious consequences. Thus, we worked on this area with the aim to determine the ability to predict difficult visualisation of larynx using the following preoperative airway predictors: MMC (Modified Mallampati Classification), RHSMD (Ratio of Height to Sternomental Distance), RHTMD (Ratio of Height to Thyromental) and HMDR (Hyomental Distance Ratio) and comparison of these with WRSS (Wilson Risk Sum Score), in isolation and in combination. METHODS A double-blind, prospective study was carried out on 300, ASA grade I or II patients posted for elective surgery in supine position under general anaesthesia. Different parameters were recorded in pre-op period and Cormack-Lehane grading and difficulty of intubation was recorded at the time of intubation. Chi Square test and receiver operating curve were used to assess the association of all the airway tests and various combinations with CL grading. Cohen’s kappa was calculated to determine the strength of agreement between laryngoscopy grade and various tests in isolation and combinations. RESULTS In our study, highest strength of agreement was found with WRSS of 0.925 (0.873 - 0.976) and only a fair agreement was seen with HMDR (κ = 0.319). RHSMD and combination of RHSMD + MMC showed good strength with kappa of 0.638 and 0.634 respectively. CONCLUSIONS No single test or group of tests was able to predict all cases of difficult laryngoscopy at the preoperative airway assessment. Wilson Risk Sum Score was found to be the best predictor of difficult laryngoscopy when compared to MMC, RHTMD, RHSMD and HMDR in isolation and any possible combination. KEYWORDS Difficult Laryngoscopy, Difficult Intubation, Wilson Risk Sum Score, Airway, RHSMD, RHTMD

Comparison of the Upper Lip Bite Test (ULBT) with the Ratio of Height to Thyromental Distance (RHTMD) for the Prediction of Difficult Laryngoscopy in Apparently Normal Patients

Comparison of the Upper Lip Bite Test (ULBT) with the Ratio of Height to Thyromental Distance (RHTMD) for the Prediction of Difficult Laryngoscopy in Apparently Normal Patients